package com.shujia.spark.streaming

import org.apache.spark.SparkConf
import org.apache.spark.streaming.dstream.{DStream, ReceiverInputDStream}
import org.apache.spark.streaming.{Durations, StreamingContext}

object Demo9Window {
  def main(args: Array[String]): Unit = {


    val conf: SparkConf = new SparkConf()
      .setAppName("streaming")
      .setMaster("local[2]")

    val ssc = new StreamingContext(conf, Durations.seconds(5))
    ssc.checkpoint("data/checkpoint")

    val linesDS: ReceiverInputDStream[String] = ssc.socketTextStream("master", 8888)


    val wordsDS: DStream[String] = linesDS.flatMap(_.split(","))

    val kvDS: DStream[(String, Int)] = wordsDS.map((_, 1))

    /**
      * 统计最新15秒单词的数量，每隔10秒统计一次
      *
      * reduceByKeyAndWindow；滑动窗口，有状态算子
      *
      * 热门商品统计
      *
      */
    /* val countDS: DStream[(String, Int)] = kvDS.reduceByKeyAndWindow(
       (x: Int, y: Int) => x + y,
       Durations.seconds(15), //窗口大小
       Durations.seconds(10) //滑动时间
     )*/


    //优化重复计算
    //需要指定checkpoint，保存之前计算结果
    val countDS: DStream[(String, Int)] = kvDS.reduceByKeyAndWindow(
      (x: Int, y: Int) => x + y,
      (x1: Int, y1: Int) => x1 - y1,
      Durations.seconds(15), //窗口大小
      Durations.seconds(10) //滑动时间
    )


    //可以将结果为0的过滤掉
    countDS.filter(_._2 != 0).print()

    //启动spark streaming
    ssc.start()
    ssc.awaitTermination()
    ssc.stop()

  }

}
